Twenty-seven patients were selected by one examiner (A.H.) for further evaluation, including uncertain and borderline cases. At the joint evaluation11 patients, each with one possible lesion, were excluded. Eight were recorded as having residual roots and three normal morphology.
Sixteen of the 210 patients examined were found to have IO. Fourteen had one lesion, one had two lesions and another one had three lesions. Eight patients (50%) were females as compared to 63% females in the whole patient group, indicating no sex predilection (P = 0.18, chi square). The mean age of the patients with IO was 47 years as compared to 44 years for the rest of the patient group, indicating no significant difference (P = 0.25, Mann-Whitney). The majority of the 19 lesions were found in the mandible, 11 in the molar area and three in the premolar area. Three lesions were found in the maxillary molar area and two in the premolar area. The maximum diameter was 15 mm as measured directly on the film. Follow-up after 10-17 years.
Seventeen lesions remained unchanged, one showed reduced size, whilst one had disappeared. The latter was in a female aged 40 years at the baseline examination and 57 years at the follow-up (Fig.1). At the follow-up, remnants of the sclerotic structure were hardly visible in the region of the maxillary second premolar. This was the only lesion with a location corresponding to an earlier alveolus. The same patient had two other lesions, in the mandibular right and left molar areas, respectively.
One new lesion appeared. Whilst the region of a first mandibular molar now showed the typical IO appearance, the retrospective viewing of the same region 13 years earlier clearly showed a residual root. Follow-up after 20-27 years.
The number of individuals that could be examined at the second follow-up was reduced from 210 to 130. Eight patients with nine IO were thus lost, and eight patients with one lesion each could be followed. Two lesions - which at the first follow-up were unchanged - now showed reduced size (Fig. 2). Six lesions remained unchanged (Fig. 3). Two new lesions occurred, one in the first maxillary molar region and the other in the second mandibular molar area. In both the cases, residual roots were observed in the radiographs taken 10 years earlier.
Figure 1. Osteosclerotic lesion in a 40-year-old female, located in the alveolar area of the first maxillary premolar (left). Seventeen years later, the lesion was recorded as disappeared, with hardly any sclerotic structures being visible (right).
Figure 2. Osteosclerotic lesion in a 42-year-old female, located in the alveolar process in the area of the distal root of the first mandibular molar (right). After 25 years, the size is somewhat reduced; especially the contour of the distal root can now be seen (left).
Figure 3. Osteosclerotic lesion in a 44-year-old male, located in the central portion of the alveolar process of a missing mandibular first molar (left). No change is seen after15 years (middle). Also after 25 years it remains unchanged (right); subtle deviations in appearance were ascribed to exposure variables.